Overflow placement and number, the benefits?

[Oberst Hajj]

Are there any benefits to the number or placement of the overflow(s)? I realize using an external overflow will free up room in the tank. But on an internal setup, does the placement or number of overflows matter?

 

[tinkerman]

The biggest facters will be with teeth will cut down surface skimming. No teeth better surface skimmig. The longer the overflow the thiner the water drawen from the surface and will give better surface skimming and make it quieter.

 

[Oberst Hajj]

Thanks tinkerman. As an example, two 4 inch overflows would be better than one 7 inch overflow for surface skimming? How would that effect noise?

 

[tinkerman]

A coast to coast would be the best for surface skimming. we'll use some examples. Lets use a 75 gal rr tank 2 center overflows will skim more than 2 corner overflows. With this same 75 gal rr tank if you did a corner overflow on just one side you may end up with that dusty look on the water surface on the other end of the tank, because it doesn't surface skim as well. if you did a overflow that is 24" long with no teeth, and you wanted teeth you would need to make it 48" long to be just as good. The pump and overflow size should be matched to keep the noise down. Using teeth will add noise to the system unless you have very little flow through them. You want your water flowing over the overflow and straight down not flowing over the overflow and pouring into the overflow. If you can keep the water flowing into the overflow under 1/4" you should get good surface skimming and keep noise down. If you do a rr tank look into the herbie design if you want it silent. If you drill it your self i would do herbie or beananimal design.

 

[Jgomez324]

+1 Tinkerman.
I have a 75 gallon corner overflow and I had to put a power head up high opposite of the overflow to get rid of the nasty looking dust on that Opposite side of the tank.

 

[tinkerman]

There are varaibles that come into play and tank size would help with opinions. Jgomez324 have you tried turning your return pump down so you get a thiner layer of water going into the overflow? This may help pull more surface water into the overflow.

 

[Jgomez324]

There are varaibles that come into play and tank size would help with opinions. Jgomez324 have you tried turning your return pump down so you get a thiner layer of water going into the overflow? This may help pull more surface water into the overflow.

I thought about that because my water overflows at a high rate about 1" above the teeth I'm gonna turn it down.

 

[Oberst Hajj]

This is all interesting. A couple of follow on questions if you don't mind tinkerman.

1. What advantages do teeth in an overflow give you?

2. Coast to coast, do that mean an overflow the entire length of the tank?

You want your water flowing over the overflow and straight down not flowing over the overflow and pouring into the overflow.

By this you mean you want it to run down the back of the overflow wall instead of pouring over the wall and falling into the overflow area?

 

[tinkerman]

The big reason people want teeth is to keep snails and fish out of their overflow. Yes entire length of tank. "By this you mean you want it to run down the back of the overflow wall instead of pouring over the wall and falling into the overflow area?" Correct

 

[Oberst Hajj]

Thank you for all the info. Looking at most of the tanks out there, most of them have shorter overflows. Either in the corners are one or two in the center. Is this just because they are trying to save space inside the tank?